JPS60203975A - Control method of developer - Google Patents

Abstract

PURPOSE:To form a stable developer layer without clogging of a trimmer by disposing repulsive magnetic poles of the same pole having prescribed magnetic force on the upstream side and downstream side facing a blade for controlling a one-component magnetic developer layer. CONSTITUTION:The thickness of a developer layer formed on an image carrying body 5 by a one-component developer 3 is controlled by a control blade 6. Repulsive poles N1, N2 of the same pole are disposed to a magnet roll 4 facing the blade 6 and the intensity of the magnetic pole N2 on the outlet side in the control part is made larger than the magnetic pole N1 on the inlet side, by which the accumulation of the developer 3 to be trimmed and the uneven conveyance of the developer in the stage of trimming are prevented. The developer chains which are held erected in the control part by the repulsion of the same pole are cut by the blade 6, by which the amt. of the developer to be stuck to the carrier 5 is decreased. The stable developer layer is thus formed on the image carrying body without clogging of the trimmer.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a developer regulation method for regulating the layer thickness of a one-component magnetic developer layer on a developer carrier in -component development.

BACKGROUND ART Conventionally, in electronic copying machines and the like, a device as shown in FIG. 1 is generally used as a one-component developing device for developing an electrostatic latent image on an image carrier using a -component magnetic developer. has been done. In FIG. 1, reference numeral 1 denotes an image carrier capable of holding an electrostatic latent image 2, and a developing device is disposed close to and facing the image carrier 1.

The developing device has a magnet roll 4 in which a plurality of magnetic poles fixed so as not to rotate are arranged alternately,
A nonmagnetic cylindrical developer carrier 5 is rotatably fixed around the magnet roll 4, and a developer carrier 5 is disposed above the developer carrier 5 in order to regulate the layer thickness of the developer layer on the developer carrier 5. The developer carrier 5 has a regulating blade 6 arranged in a hopper 7 for containing the magnetic developer 3, and the developer carrier 5 is disposed close to the image carrier 1. has been done.

In such a developing device, the magnetic developer 3 supplied into the impeller 7 is held on the surface of the developer carrier 5 by the magnetic force of the magnet roll 4, and as the developer carrier rotates, The image carrier I and the developer carrier 5 are fed into a developing area where they face each other, and the electrostatic latent image 2 is developed there.

Various types of blades have been proposed as means for regulating the thickness of the developer layer on the developer carrier 5.

However, in a developing method in which a magnetic blade is used and the amount of developer adhering to the developer carrier 5 is set to 1 to 3 my/cnI, in order to eliminate fogging in the background area, the developing method is applied to the developer carrier 5. It was necessary to use an alternating electric field as a bias (not shown).On the other hand, a DC bias development method uses a non-magnetic blade to regulate the amount of developer adhered on the developer carrier 5 to 10 to 3 degrees. For example, the density of the copied image does not decrease linearly with respect to the density of the original document, and the density of the copied image drops rapidly in the low density area of the original, which is the so-called poor reproduction of low-density lines, and line Image quality defects such as thickening of the line and fringing phenomenon where spots are attached around the line were observed.

In order to solve the above problem, the amount of developer attached should be increased from 3 to 6 cm.
A regulating method (trimming method) has been attempted, but it is necessary to set the regulating part gap (trimmer gap) between the regulating blade and the developer carrier 5 to 0.1 to 0.2 +u.
Trimmer clogging occurred. In addition, as a method to improve this trimmer clogging, attempts have been made to use the magnetic force of the magnet roll facing the regulating section as a repellent pole, but although this method improves the trimmer clogging, the developer does not flow into the repelling magnetic pole. A stagnation occurred and a stable developer layer could not be obtained.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a developer regulating method that is free from problems such as the trimmer clogging and which can form a stable developer layer on a developer carrier.

Structure of the Invention The developer regulating method according to the present invention is a method for regulating one-component magnetic developer on a developer carrier using a regulating blade as described above. It is characterized in that it is extremely repulsive and the strength of the magnetic force is made stronger on the regulating part mouth side than on the regulating part entrance side.

Effects and aspects of the invention The effects and various aspects of the invention will be described below with reference to the drawings. For convenience of explanation, parts having the same functions as those of the conventional device shown in FIG.

FIG. 2 shows a schematic configuration of an example of a one-component developing device employing the developer regulating method according to the present invention.

A homopolar repelling magnetic pole (N1°Nt) is arranged at a position on the magnet roll 4 facing the regulation grade 6 made of a non-magnetic material. The same-polarity repelling magnetic pole (N1°N, ) is the third
It has a magnetic force gradient as shown in the figure.

Preferably, the magnetic force on the regulating section entrance side (N1) is 3, so that the magnetic force is stronger on the regulating section entrance side as well as on the regulating section entrance side.
00 to 700 Gauss (Gatbsz) *Regulation part mouth side (
Nt) magnetic force is set to be 800 to 1200 Gauss.

The effect of regulating the thickness of the developer layer on the developer carrier 5 according to the present invention will be described with reference to FIGS. 4 and 5.

Fig. 4 shows the flow of the developer 3 when the magnetic force of each magnetic pole of homopolar repulsion is set to be the same (Ns - Nt - 800 cows).In such a case, the rotation direction of the developer carrier 5 Accordingly, a developer reservoir is generated on the upstream side of the flow of the developer 3 (see FIG. 4).

For this reason, when trimming is performed at this position, uneven conveyance occurs on the developer carrier, and a stable developer layer cannot be obtained. On the other hand, if the homopolar repulsive magnetic pole is set to 1, for example, N□-5
In the case of homopolar repulsion with magnetic force gradients such as 00 Gauss, S, N, and -1000 Gauss, the flow of the developer 3 is shown as shown in Fig. 5, and the developer sump is no longer generated. No uneven conveyance occurs during trimming. Further, by using the homopolar repelling poles, the regulating blade cuts the developer chain while the developer chain is standing in the regulating portion, so that the amount of adhesion on the developer carrier can be reduced.

Embodiment In the apparatus shown in FIG. 2, the configuration of the homopolar repulsive magnetic poles (N8, N2) of the magnet roll 4 of the regulating section is such that the regulating section has a magnetic force N on the input side, -500 Gauss, and a magnetic force N on the output side. -1000
Gauss, and a non-magnetic regulating blade 6 as a regulating member.
When the developer layer was controlled by setting the gap between the non-magnetic cylindrical developer carrier 5 and the regulation blade 6 to 0.3 ms, the amount of developer deposited was 6 frames. However, a uniform developer layer was formed. Also, for trimmer clogging.
However, it was confirmed that there were no problems. Also, surprisingly, no unevenness in conveyance on the developer carrier occurred.

Effects of the Invention As described above, according to the developer regulating method of the present invention, the magnetic force at the position facing the regulating blade is homopolar repulsion, and the strength of the magnetic force is greater than that on the regulating part entrance side. By being strengthened on the oral side.

The accumulation of developer generated on the entrance side of the regulating portion is suppressed, and a uniform developer layer can be stably formed on the developer carrier without clogging the trimmer.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of a conventional one-component developing device. FIG. 2 is a schematic explanatory diagram showing an example of a one-component developing device using the developer regulating method according to the present invention, FIG. 3 is a graph showing an example of the magnetic force distribution of homopolar repelling magnetic poles, and FIGS. The figure is an explanatory diagram of the operation of a developer regulating method using homopolar repelling magnetic poles. DESCRIPTION OF SYMBOLS 1... Image carrier, 3...-component magnetic developer, 4...
・Magnet roll, 5...Developer carrier, 6...
regulation blade. Figure 1 Figure 3 Figure 4' Figure N5

Claims (1)

[Claims] 1. A non-magnetic cylindrical developer carrier having a magnet roll made up of a plurality of magnetic poles fixed so as not to rotate therein, and rotatably pivoted around the magnet roll. In the above developer regulation law, which regulates the one-component magnetic developer using a regulation blade, the magnetic force at the position facing the regulation blade is homopolar repulsion, and the strength of the magnetic force is set to be higher than that on the regulation part entrance side. A developer regulation method characterized by making the developer stronger on the mouth side. 23 The magnetic force of the homopolar repulsion is 300~
700 gauss, 8o on the regulating part mouth side. ~! 200 Gauss. The developer regulating method according to claim 1.